Updated 7.05pm
Twitter on Friday suspended sign-ups for a new paid checkmark system introduced just last week, as it scrambled to curb fake accounts that have proliferated since Elon Musk's takeover.
The company also reinstated a grey "official" badge on some accounts.
The U-turn was the latest of a string of chaotic developments at the social network, which has lurched back and forth on the question of account verification since Musk's $44 billion buyout late last month.
The @TwitterSupport account tweeted early Friday that a grey checkmark indicating an "official" account was coming back, only days after it was introduced -- then almost immediately scrapped.
"To combat impersonation, we've added an 'Official' label to some accounts," the profile announced.
The rollout of the label appeared inconsistent: it appeared briefly then disappeared from the network's own account, @Twitter.
By Friday morning, the firm had also disabled sign-ups for Twitter Blue, the feature touted by free-speech proponent Musk as bringing "power to the people" by offering ordinary users a verified blue tick -- until then reserved for prominent accounts -- for $8 per month.
An internal memo for Twitter staff, obtained by US media including The Washington Post, confirmed the feature had been temporarily disabled to "help address impersonation issues."
In introducing the paid blue-check verification system, Musk had warned that Twitter would suspend fake accounts not clearly marked as parody.
But accounts impersonating public figures and businesses had continued to spread -- with NBA star LeBron James and former British prime minister Tony Blair among those targeted.
US drugmaker Eli Lilly was forced to issue an apology Thursday after a fake account -- stamped with a purchased blue tick -- tweeted that insulin was to be made available for free.
The fake account was removed, and the company put out a statement of apology.
The turmoil at Twitter has raised concerns about the potential for serious damage, should nefarious actors successfully pose as official representatives of powerful companies or government entities.
And the disarray -- which saw two more top security executives quit on Thursday -- drew a rare warning from the Federal Trade Commission which said it was tracking the developments with "deep concern."
"We are tracking recent developments at Twitter with deep concern," an FTC spokesperson said in a statement.
"No CEO or company is above the law, and companies must follow our consent decrees," the spokesperson added, referring to past commitments by Twitter to obey US privacy rules.
Violating FTC decisions could cost Twitter millions of dollars in fines.
Mass resignations
The same day, Musk informed Twitter employees the site was burning through cash dangerously fast, raising the spectre of bankruptcy if the situation was not turned around.
The warning came a week after he fired half of Twitter's 7,500 employees.
Key security executives resigned from the platform over the past days.
"I've made the hard decision to leave Twitter," tweeted chief security officer Lea Kissner, who reportedly stepped down with other key privacy or security executives.
In the most extraordinary exit, US media reported that Yoel Roth -- the site's head of trust and safety -- stepped down just a day after staunchly defending Musk's content moderation policy to advertisers.
Late on Thursday, Roth's Twitter bio identified him as "Former Head of Trust & Safety at @Twitter."
Media reports had said Robin Wheeler, who held a key role linking Twitter with advertisers and was considered a key Musk ally inside the company, was leaving but late Thursday she tweeted: "I'm still here."
Musk admits concerns
For the first time since the layoffs, the 51-year-old entrepreneur addressed his remaining employees on Thursday and urged them to help the site reach one billion users, according to employee text messages seen by AFP.
Musk also warned that the company was bleeding cash and expressed fear about the effects of the poor economy on his newly bought business.
"You may have noticed I sold a bunch of Tesla stock. The reason I did that is to save Twitter," he is reported to have said.
Wedbush analyst Dan Ives warned that the Twitter episode could have serious repercussions for electric car manufacturer Tesla.
"Brand destruction is our biggest worry with this Twitter circus show. It's that simple and I can't ignore it for Tesla stock," Ives wrote on the site.
Twitter is also crippled by the decision of advertisers to stay away from the platform, concerned about Musk's plans.
The tycoon announced he was ending work-from-home policies at Twitter, which had been a widespread practice at the San Francisco-based company.
"If you don't show up at the office, resignation accepted," he told employees.